This invention relates generally to material handling apparatus and more particularly to a container having a non-circular base supporting a flexible bag for sealingly holding a load of fluent material, such as a fine granular, particulate or powdered material.
The container of this invention represents an improvement over the container disclosed in coassigned U.S. Pat. No. 4,149,755 and commercially available from the assignee of this invention, Semi-Bulk Systems, Inc. of St. Louis, Mo. under registered trademark AIR PALLET. The latter container has a pallet base with a generally circular horizontal periphery which supports a generally cylindric bag of flexible material for containing a load of powder or other fluent material. While this container has proven to be generally satisfactory, the generally circular periphery of the pallet base and the corresponding generally cylindric shape of the bag is not space efficient for packing or grouping a number of containers closely together in side-by-side relation (e.g., loading a truck). A substantial amount of space is wasted between pallet bases because of their generally circular shape. This results in higher storage and transportation costs. Moreover, a bag of generally circular shape in transverse (horizontal) cross section is somewhat unstable and has a tendency to tilt on its base, especially if the material in the bag is relatively loosely packed.
While non-circular (e.g., rectangular) containers are more space efficient, it is difficult to obtain a sealing connection between a bag and a base of non-circular configuration. Annular clamp designs of the type disclosed in the aforementioned U.S. Pat. No. 4,149,755 will not provide a uniform seal when used on a container which is rectangular, for example. Even if the clamp is designed to have a rectangular shape corresponding to that of the base, the long straight sections of the clamp corresponding to the straight sides of the base and bag cannot provide a sufficient inward force to seal the bag against the base. Consequently, a sealing connection between the bag and the base is not achieved and leakage results. It will be noted in this regard that the product in such containers is often conditioned (fluidized) by the introduction of pressurized air into the bag to facilitate unloading of product from the bag. Unless there is a tight seal between the bag and the container, pressurized air and/or product will leak from the bag, which reduces the efficiency of the unloading process.